Sanderson, William
Best known to me as Larry from Newhart. I also know him from Blade Runner; and Bar Karma; and a bit of voice work. Oh, also I have long had this crazy theory that he's an immortal, and could probably explain the truth about the disappearance of the Roanoke Colony....

Shatner, William
First and foremost, he is Kirk, from Star Trek. There's also Boston Legal; and Invasion Iowa; and a couple eps of The Twilight Zone (including "Nightmare at 20,000 Feet," which is one of the more memorable episodes of the entire series); and he played Juliet's dad in a couple episodes of Psych. Also voice work in an ep of My Little Pony: Friendship Is Magic. Oh, and of course he's done plenty of commercials (most notably for Priceline). And there's his (in)famous rendition of "Rocket Man," which is truly incredible. And I also enjoyed his rendition of "Common People." Anyway, no doubt I've seen him in other stuff, I dunno...

Valley, Mark
He was good in Keen Eddie. Didn't much care for the way he was used in Boston Legal, but he had his moments. He was decent in Human Target. And there was Crisis. I may have seen some other stuff I don't really remember. Though there was at least one episode of Fringe, but I stopped watching that too early to see much of his work in it.

Verica, Tom
No doubt I saw him in various things before this, but the first thing I really remember him from is the TV series State of Grace. And no doubt I've seen him in various things since then, but the main one I remember is American Dreams. And there were a couple eps of The 4400.